1. Field of the Invention
Embodiments of the present invention relate to burn-in of semiconductor devices.
2. Related Art
Semiconductor devices (e.g., microprocessors) are screened for defects by performing burn-in operations that subject the devices to test conditions including an elevated temperature test condition. However, due to variations in burn-in power, ambient temperature, air flow and heat sink performance, all devices under test may not experience the same temperature during testing.
Variation in the wafer fabrication process is a primary cause of variation in burn-in power. Fabrication process variations can cause leakage current to differ from one part to another by as much as 100 percent. While leakage current from a chip is proportional to the number of transistors on the chip, leakage current is inversely proportional to the critical dimension of the transistors. Increasing the number of transistors and decreasing the size of the transistors, which are currently accelerating trends in chip making, aggravate the situation. A solution that can ameliorate problems caused by variations in burn-in power would be advantageous.